Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
2
|
| pubmed:dateCreated |
1992-10-30
|
| pubmed:abstractText |
Hydrogen peroxide is more toxic to mammalian cells at 37 degrees C than 0 degree C at all concentrations studied. Histone-free nuclei (nucleoids) extracted from treated cells have a reduced ability to maintain positive DNA supercoiling, with the maximum effect at the higher temperature. Prior exposure of cells to sodium ascorbate at 0 degree C increased both toxicity and the inhibition of nuclear supercoil rewinding. After exposure at 0 degrees C, normal levels of supercoiling returned with both a fast and a slow component, kinetics characteristic of DNA single-strand break repair; the fast component was eliminated when cells were exposed at 37 degrees C due to in situ rejoining. At least a portion of the lethal lesions induced by hydrogen peroxide are DNA double-strand breaks (dsb) because the dsb repair-deficient mutant, xrs-5, is approximately two to three times more sensitive than wild-type cells over the initial portion of the survival curve. However, the increased toxicity found after exposure at 37 degrees C is observed equally in both cell lines, indicating that temperature-dependent cell killing is not directly linked to DNA dsb. It is suggested that cell killing at 37 degrees C is mediated through two linked processes. First, hydrogen peroxide may disrupt cation-stabilized nuclear supercoiling by direct ion oxidation. Second, as a part of the oxidation process, hydrogen peroxide will produce potentially cytotoxic free radicals close to the DNA-linked metal site, limited in extent only by the presence of chemicals capable of reducing metal ions prior to reoxidation.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Oct
|
| pubmed:issn |
0014-4827
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
202
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
376-80
|
| pubmed:dateRevised |
2005-11-17
|
| pubmed:meshHeading |
pubmed-meshheading:1397090-Animals,
pubmed-meshheading:1397090-Ascorbic Acid,
pubmed-meshheading:1397090-CHO Cells,
pubmed-meshheading:1397090-Cell Death,
pubmed-meshheading:1397090-Cell Line,
pubmed-meshheading:1397090-Cricetinae,
pubmed-meshheading:1397090-DNA, Superhelical,
pubmed-meshheading:1397090-DNA Repair,
pubmed-meshheading:1397090-Hydrogen Peroxide,
pubmed-meshheading:1397090-Kinetics,
pubmed-meshheading:1397090-Temperature
|
| pubmed:year |
1992
|
| pubmed:articleTitle |
Hydrogen peroxide lethality is associated with a decreased ability to maintain positive DNA supercoiling.
|
| pubmed:affiliation |
Loyola-Hines Department of Radiotherapy, Illinois 60141.
|
| pubmed:publicationType |
Journal Article
|